St. Margarets Bay Islands Nature Reserve protects eleven islands in St. Margarets Bay and a two-hectare (ha) parcel on Troop Island. The eleven islands include: Ant Island, Potato Island, Big Thrum and Little Thrum Islands, Lukes Island, Shut-In Island, Mink Island, Hubley Island, Wreck Island, Jack Island, and Horse Island.

The islands range in size from 1/8 ha to over 40 ha and include coastal barrens and forest, cliffs, beaches, dunes and nesting habitat for rare birds.

The St. Margarets Bay Stewardship Association maintains an active stewardship program for these and other islands. Camping and picnicking at Lukes Island is permitted, provided leave-no-trace principles are followed.

The parcel on Troop Island was transferred to the Province for protection by the Nova Scotia Nature Trust in 2015.